p  1 1        » 


<^ 


Issued  August  24,  1914. 

HAWAII  AGRICULTURAL  EXPERIMENT  STATION, 

E.  V.  WILCOX,  Special  Agent  in  Charge. 


Bulletin    No.  35. 


ABSORPTION  OF  FERTILIZER  SALTS 
BY  HAWAIIAN  SOILS. 


BY 

Wm.  McGEORGE, 

ASSISTANT  CHEMIST. 


UNDER  THE  SUPERVISION  OF 

OTTTCE  OF  EXPERIMENT  STATIONS, 

U.  8.   DEPARTMENT   OF    AGRICULTURE. 


WASHINGTON: 

GOVERNMENT   PRINTING   OFFICE. 

1914. 


Issued  August  24,  1914. 

HAWAII  AGRICULTURAL  EXPERIMENT  STATION, 

E.  V.  WILCOX,  Special  Agent  in  Charge. 


Bulletin    No.  35. 


ABSORPTION  OF  FERTILIZER  SALTS 
BY  HAWAIIAN  SOILS. 


BY 

Wm.  McGEORGE, 

ASSISTANT  CHEMIST. 


UNDER  THE  SUPERVISION  OF 
OFFICE  OF  EXPERIMENT  STATIONS, 

U.  8.   DEPARTMENT   OF    AGRICULTURE. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1914. 


HAWAII  AGRICULTURAL  EXPERIMENT  STATION,  HONOLULU. 

[Under  the  supervision  of  A.  C.  True,  Director  of  the  Office  of  Experiment  Stations,  United  States 

Department  of  Agriculture.] 

Walter  H.  Evans,  Chief  of  Division  of  Insular  Stations,  Office  of  Experiment  Stations. 

STATION  STAFF. 

E.  V.  Wilcox,  Special  Agent  in  Charge. 
J.  Edgar  Higgins,  Horticulturist. 
W.  P.  Kelley,  Chemist. 

C.  K.  McClelland,  Agronomist. 

D.  T.  Fullaway,  Entomologist. 
Wm.  McGeorge,  Assistant  Chemist. 
Alice  R.  Thompson,  Assistant  Chemist. 
C.J.  Hunn,  Assistant  Horticulturist. 
V.  S.  Holt,  Assistant  in  Horticulture. 
C.  A.  Sahr,  Assistant  in  Agronomy. 

(2) 


LETTER  OF  TRANSMITTAL. 


Honolulu,  Hawaii,  September  29,  1913. 
Sik:  I  have  the  honor  to  submit  herewith  and  recommend  for 
publication  as  Bulletin  No.  35  of  the  Hawaii  Agricultural  Experiment 
Station,  a  paper  on  the  Absorption  of  Fertilizer  Salts  by  Hawaiian 
Soils,  by  William  McGeorge,  assistant  chemist.  In  order  to  be  in 
position  to  recommend  a  rational  program  for  the  management  of 
Hawaiian  soils  it  has  been  found  necessary  to  make  a  study  of  all 
the  properties  of  these  soils.  In  the  present  paper  many  interesting 
points  are  brought  out  upon  the  subject  of  the  fixing  power  of  these 
soils  for  different  fertilizer  salts.  It  appears  that  the  concentration 
of  a  soil  solution  depends  perhaps  more  upon  the  fixing  power  of  the 
soils  than  upon  the  solubility  of  the  salt. 
Respectfully, 

E.  V.  Wilcox, 
Special  Agent  in  Charge. 
Dr.  A.  C.  True, 

Director  Office  of  Experiment  Stations, 

U.  S.  Department  of  Agriculture,  Washington,  D.  C. 

Recommended  for  publication. 
A.  C.  True,  Director. 

Publication  authorized. 

D.  F.  Houston,  Secretary  of  Agriculture. 

(3) 


CONTENTS. 


Object  of  work 5 

Soil  types  used 5 

Method 6 

Absorption  of  phosphoric  acid 6 

Absorption  of  potash 10 

Absorption  of  nitrogen 12 

Ammonium  sulphate 12 

Sodium  nitrate 14 

Absorption  of  fertilizer  salts  by  fresh  and  air-dried  soils 16 

Absorption  of  phosphoric  acid 16 

Absorption  of  potash 19 

Absorption  of  nitrogen 20 

Ammonium  sulphate 20 

Sodium  nitrate 21 

Absorption  of  fertilizer  salts  when  applied  in  mixtures,  and  the  effect  of  heat 

and  antiseptics 22 

Absorption  of  phosphoric  acid 22 

Absorption  of  potash 24 

Absorption  of  nitrogen 26 

Ammonium  sulphate 26 

Sodium  nitrate 27 

Removal  of  absorbed  salts 27 

Removal  of  absorbed  phosphate 28 

Removal  of  absorbed  potash 28 

Removal  of  absorbed  nitrogen 29 

Summary 29 

Acknowledgments 32 

(4) 


ABSORPTION  OF  FERTILIZER  SALTS  BY  HAWAIIAN 

SOILS. 


In  undertaking  investigations  on  soil  fertility  it  is  very  necessary 
to  have  some  knowledge  of  the  absorptive  or  fixing  power  of  a  soil, 
since  this  factor  is  one  of  prime  importance  in  the  successful  use  of 
fertilizers  and  varies  greatly  with  the  physical  structure,  the  organic 
matter  content,  and  other  factors  of  a  chemical  and  biological  nature. 

OBJECT  OF  WORK. 

The  object  of  the  work  here  presented  was  to  give  some  under- 
standing of  the  absorptive  power  of  Hawaiian  soils  for  fertilizer  salts. 
These  soils  contain  an  abnormally  high  percentage  of  iron  and  alu- 
minum compounds,  and  from  their  physical  condition  would  be 
expected  to  have  a  high  fixing  power.  Many  of  the  soil  types  of  the 
islands  also  contain  large  amounts  of  organic  matter  and  humus. 
J.  T.  Crawley  x  carried  on  some  experiments  with  Hawaiian  soils  to 
determine  the  effect  of  irrigation  upon  added  fertilizer  salts.  He 
found  phosphoric  acid  to  be  firmly  fixed,  while  ammonium  sulphate 
and  potassium  sulphate  were  not  so  strongly  fixed. 

SOIL  TYPES  USED. 

Soils  representing  in  a  general  way  the  important  types  of  the 
islands  were  selected  for  the  work.  The  following  table  shows  the 
chemical  composition  of  the  soils,  as  determined  by  digestion  in 
hydrochloric  acid  of  specific  gravity  1.115: 

Composition  of  soils  used  in  the  experiments. 


Constituents. 


Moisture 

Volatile  matter 

Insoluble  matter 

Ferric  oxid  (Fe203; 

Alumina  (A1203) 

Titanium  oxid  (Ti02). . . . 
Manganese  oxid  (Mn304;. 

Lime(CaO) 

Magnesia  (MgO) 

Potash  (K20) 

Soda(Na20) 

Sulphur  trioxid  (SOa). .. . 
Phosphoric  acid  (P^ >»)  -  - 


Soil  No.     Soil  No. 
292.  448. 


Per  cent. 

7.65 

8.42 

38.49 

16.63 

12.85 

2.00 

.24 

1.84 

8.71 

.39 

1.36 

.08 

.57 


Per  cent. 

15.00 

25.58 

15.10 

19.20 

16.64 

4.20 

.06 

.50 

1.80 

.15 

.68 

.53 

.29 


Soil  No. 

428. 


Per  cent. 

14.95 

22.24 

34.99 

8.24 

10.73 

3.20 

.20 

1.91 

2.24 

.24 

1.40 

.45 

.22 


Soil  No. 
474. 


Per  cent. 

13.59 

20.01 

33.  77 

7.00 

1G.79 

1.80 

.07 

3.80 

.85 

.72 

.10 

.45 

2.18 


Soil  No. 
517. 


Per  cent. 
3.54 
13.71 
41.99 
21.76 
17.23 


i  Jour.  Amer.  Chem.  Soc.,  24  (1902),  p.  1114;  25  (1903),  p.  47. 
(5) 


Soil  No. 
518. 


Per  cent. 
3.97 
13.56 
41.53 
21.46 
18.21 


.12 
.36 
.32 
.54 
.23 
.58 
.13 


.04 
.20 
.24 
.66 
.46 
.52 
.16 


Soil  No.  292.  This  type  of  soil  occurs  in  the  lowlands  in  and  about 
Honolulu,  now  being  used  for  growing  bananas,  rice,  and  for  truck 
farming.  It  has  a  sandy  texture,  being  partly  derived  from  black  or 
volcanic  ash.  It  has  a  grayish-brown  color,  abnormally  high  mag- 
nesia content,  and  low  content  of  organic  matter. 

No.  448  represents  the  type  of  yellow  clay  scattered  throughout 
the  islands,  this  sample  being  taken  near  Hilo,  Hawaii. 

No.  428  is  a  dark  colored,  highly  organic  soil  from  Glenwood, 
Hawaii.  It  has  a  very  sandy  texture,  is  subject  to  heavy  rainfall, 
and  is  rather  unproductive. 

No.  474  is  a  sample  of  soil  from  Parker  ranch,  Waimea,  Hawaii. 
It  is  a  brown-colored  soil  of  floury  texture  and  very  productive. 

No.  517  represents  the  type  of  soil  which  is  most  abundant  in  the 
islands,  namely,  the  heavy  red  clay,  a  highly  ferruginous  type. 

METHOD. 

The  method  of  treatment  adopted  in  this  investigation  was  as  fol- 
lows: 100  grams  of  air-dry  soil  was  placed  in  glass  tubes,  1  inch  in 
diameter,  and  fitted  with  rubber  stoppers  and  pinchcock  to  regulate 
the  passage  of  the  solution  through  the  soil.  The  percolation  was  regu- 
lated to  flow  at  a  rate  of  100  cubic  centimeters  in  24  hours,  and  each 
successive  100  cubic  centimeters  of  percolate  was  analyzed.  The  salts 
used  were  sodium  nitrate,  potassium  phosphate,  and  calcium  phos- 
phate, separately  and  as  a  mixture.  One  series  was  also  heated  to 
230°  C.  and  another  treated  with  chloroform  to  determine  the  effect 
of  these  agents  upon  absorption.  All  determinations  were  made- by 
colorimetric  methods,  except  those  of  potash,  which  was  precipitated 
and  weighed  as  potassium  chloroplatinate. 

ABSORPTION  OF  PHOSPHORIC  ACID. 

In  this  series  the  percolation  was  carried  on  for  nearly  two  months, 
5  liters  of  the  solution  of  potassium  phosphate  passing  through  the  soil. 
The  solution  used  contained  about  200  parts  phosphoric  acid  (P04) 
per  million,  and  each  time  a  new  solution  was  made  up  the  strength 
was  determined  by  analysis.  Owing  to  the  fact  that  percolation 
through  a  column  of  the  soil  was  found  to  be  impossible,  due  to  the 
strong  deflocculating  effect  of  this  salt,  the  percolation  in  this  series 
was  carried  on  in  funnels.  Even  then  several  of  the  samples  filtered 
very  slowly.  The  filtrate  from  the  clay  soil  was  very  cloudy,  and  the 
percolates  became  slightly  stagnant  in  several  instances  after  the 
percolations  had  been  carried  on  for  about  one  and  a  half  months. 

In  order  to  get  a  clear  conception  of  the  fixation  of  phosphates 
it  is  necessary  to  have  some  idea  of  the  solubility  of  phosphoric  acid 
already  present  in  the  soil  when  treated  in  the  same  way  as  in  the 


experiments.  For  this  purpose  the  glass  tubes  were  filled  with  100 
grams  of  soil,  covered  with  distilled  water,  and  each  100  cubic  centi- 
meters of  filtrate  analyzed. 

Phosphoric  acid  removed  from  the  soils  by  distilled  water. 
[Expressed  in  parts  per  million  of  PO<  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

Soil  No. 
292. 

Soil  No. 
448. 

SoU  No. 
428. 

SoU  No. 
474. 

Percolates  of  Soil  No. 
100  cc.  each.        292. 

Soil  No. 
448. 

Soil  No. 
428. 

Soil  No. 
474. 

100 

6.4 

3.2 

3.8 
4.4 

3.8 
4.4 

500 5.6 

600 11.2 

700 12.0 

800 10.8 

2.8 
2.0 
2.0 
3.6 

4.6 

4.4 

6.0 

20.0 

7.0 

200 

10.8 

300 

8.8 
3.8 

5.2 

400... 

3.2 

5.0 

11.2 

The  general  tendency  of  these  soils  is  to  yield  a  solution  of  fairly 
constant  concentration.  This  is  in  direct  harmony  with  what  should 
be  expected,  namely  that  the  phosphoric  acid  is  so  firmly  retained 
by  Hawaiian  soils  that  the  first  leachings  should  not  yield  a  more 
concentrated  solution  than  those  following. 

The  following  table  shows  the  absorbing  power  of  the  soil  for  phos- 
phoric acid  in  monopotassium  phosphate  (KH2P04) : 

Absorption  of  phosphoric  acid  from  a  solution  of  monopotassium  phosphate  (KH2P04). 
[Expressed  in  parts  per  mUlion  of  PO*  in  the  percolate.] 
SOLUTION  CONTAINED  175  PARTS  PER  MILLION  PO,. 


Percolates  of   SoU  No. 
100  cc.  each.        292. 


Soil  No. 
448. 


Soil  No. 
428. 


Soil  No. 
474. 


Percolates  of 
100  cc.  each. 


Soil  No.    Soil  No.   Soil  No. 
292.  448.      ;      428. 


Soil  No. 
474. 


100 45.6  13.6  11.2  17.2  '.  2,100 

200 35.2  29.0  13.2  40.0     2,200 

300 52.0  10.4  17.2  44.0     2,300 

400 38.0  13.6  i        34.0  49.0     2,400 , 

500 39.0  9.6  19.4  36.0     2,500 

600T 48.0  11.2  15.6  I          39.0     2,600 

700 57.0  15.6  16.8  I          42.0     2,700 

800 !  27.0  36.0  36.0  55.0     2,800 

900 20.0  5.8  20.8  35.6     2,900 

1,000 17.8  5.8  27.8  41.6  i  3,000 

1,100 1  71.2  5.2  12.0  24.8     3,100 

1,200 !  37.2  6.8  13.2  40.0     3,200 

1,300 1  72.0  6.4  I        14.0  34.4  j  3,300 

1,400 ,  60.0  10.0  i        16.8  20.8     3,400 

1,500 '  76.0  .7.2  I        12.0  52.0     3,600 

1,600 72.0  5.6  |        11.6  56.0     3,800 

1,700 i  42.0  13.6  j        12.0  24.0     4,000 

1,800 64.0  9.6  8.0  20.0     4,200 

1,900 !  66.4  4.4  |          4.4  18.0     4,400 

2,000 54.4  4.0  4.0  14.8 

SOLUTION  CONTAINED  140  PARTS  PER  MILLION  P04. 

I  j  j  j                                               j 

4,600 40.0  6.0  7.6  24.0     5,000 34.4  I          4.0 

4,800 24.8  6.8  8.4  23.2 


62.8 

4.0 

5.2 

60.0 

5.2 

4.8 

60.0 

4.0 

4.0 

66.4 

5.6 

6.0 

62.8 

4.8 

4.8 

56.0 

4.8 

4.8 

44.0 

4.0 

4.8 

28.8 

4.0 

4.8 

31.2 

3.6 

4.0 

39.2 

4.4 

4.4 

21.6 

4.0 

4.0 

6.8 

5.6 

5.6 

33.6 

5.6 

5.6 

25.6 

10.0 

29.6 

20.8 

8.0 

8.8 

46.6 

10.0 

9.6 

29.6 

4.4 

6.4 

46.4 

5.2 

12.4 

34.4 

4.8 

8.0 

25.6 
38.4 
22.4 
22.4 
31.2 
16.8 
32.0 
28.8 
35.2 
32.0 
24.0 
26.4 
44.0 
36.8 
29.6 
31.2 
34.4 
48.0 
48.0 


4.0 


24.0 


Summary  of  above  table. 


SoU  No. 

PO, 
added  to 
100  gm. 

soU. 

PO< 
fixed  by 
100  gm. 

soU. 

Per  cent 
ofP04 
fixed. 

292 

Gram. 

0.8540 

.8540 

.8540 

.8540 

Gram. 

0.6872 
.8146 
.7977 
.6882 

80.6 

448 

95.5 

428 

93.3 

474 

80.7 

8 

The  amount  of  phosphoric  acid  fixed  from  a  solution  of  mono- 
calcium  phosphate  (CaH4(P04)2)  is  shown  in  the  following  table: 

Absorption  of  phosphoric  acid  from  a  solution  of  monocalcium  phosphate  (CaB^  (P04)2). 

[Expressed  in  parts  per  million  of  PO4  in  the  percolate.] 
SOLUTION  CONTAINED  232  PARTS  PER  MILLION  PO*. 


Percolates  of 
'100  cc.  each. 

Soil  No. 
292. 

Soil  No. 
448. 

Soil  No. 
428. 

Soil  No. 

474. 

Percolates  of 
100  cc.  each. 

Soil  No. 
292. 

Soil  No. 
448. 

Soil  No. 
428. 

Soil  No. 
474. 

100 

40.0 
24.0 
23.2 
50.0 

10.4 
7.2 
10.8 
14.0 

9.6 
9.2 
8.0 
14.4 

24.8 
18.4 
22.4 
41.0 

500....' 

33.0 
17.2 
13.6 

16.0 
11.6 
11.6 

15.2 
11.2 
10.4 

39.0 

200 

600 

19.2 

300 

700 

16.8 

400 

SOLUTION  CONTAINED  220  PARTS  PER  MILLION  PO*. 


800.. 
900.. 
1,000. 
1,100. 


11.6 

11.6 

11.2 

14.4 

15.6 

4.4 

6.4 

11.2 

24.0 

4.0 

4.8 

21.2 

30.4 

4.8 

6.0 

21.6 

1,200. 
1,300. 
1,400. 
1,500. 


14.4 

6.0 

6.4 

18.4 

4.0 

8.4 

28.8 

5.2 

10.0 

17.6 

4.4 

8.0 

SOLUTION  CONTAINED  132  PARTS  PER  MILLION  PO< 


11.6 
13.6 
17.2 
21.6 


1,600 

44.0 
22.4 
17.6 
17.6 

4.4 
4.0 
4.0 
4.8 

4.0 
5.6 
8.0 
7.6 

21.6 
14.4 
15.2 
14.4 

2,000 

22.  4 
21.6 
35.2 

4.0 

5.2 
5.6 

4.0 
7.2 
6.4* 

16.8 

1,700 

2,100...    . 

16.8 

1,800 

2,200... 

17.6 

1,900 

SOLUTION  CONTAINED  200  PARTS  PER  MILLION  P04 


Soil  No. 


PO* 
added  to 
100  gm. 

soil. 


2,400 

36.0 
22.4 

12.4 
4.0 

17.2 

7.2 

25.6 
12.8 

2,800 

2,900 

22.4 
20.8 

12.4 
5.2 

10.0 

5.6 

18.4 

2,600 

16.4 

SOLUTION  CONTAINED  240  PARTS  PER  MILLION  PO<. 

• 

3,100 

39.2 
76.0 

4.0 
4.8 

8.4 
8.0 

24.8 
36.8 

3,500 

16.8 

5.2 

5.6 

18.4 

3,300 

SOLUTION  CONTAINED  240  PARTS  PER  MILLION  PO*. 

3,700 

28.0 

10.0 

12.0 

14.0 

3,900 

24.0 

4.0 

6.4 

13.6 

Summary  of  above  table. 

P04  fixed 
by  100 
em.  soil. 


Per  cent 
of  PO< 
fixed. 


292 

448 
428 
474 


Oram. 
0. 8308 
.8308 
.8308 


Gram. 

0. 7190 

.8043 

.7966 

.7516 


86.4 
96.7 
95.8 
90.4 


9 

The  series  reported  in  the  above  table  was  started  in  glass  tubes, 
100  grams  of  soil  being  used  in  each  instance,  but  it  was  found  neces- 
sary to  transfer  the  soils  to  funnels,  as  there  was  no  percolation  at  all 
through  soil  No.  474,  and  it  was  extremely  slow  in  Nos.  292,  448,  and 
428.  The  extracts  all  came  through  clear  for  about  one  month, 
after  which  they  began  coming  through  cloudy,  and  when  the  series 
was  stopped  the  percolation  was  very  slow  even  in  the  funnels. 

Phosphoric  acid  being  the  constituent  of  phosphates  which  forms 
insoluble  compounds  with  the  bases  always  present  in  soils,  such  as 
iron,  aluminum,  titanium,  lime,  and  magnesium,  it  is  not  very  difficult 
to  understand  the  retention  of  soluble  phosphoric  acid  by  soils.  In 
the  presence  of  sufficient  calcium  carbonate  the  application  of  soluble 
phosphoric  acid  will  result  in  a  " reversion"  of  the  phosphate,  i.  e., 
the  formation  of  the  less  soluble  dicalcium  phosphate  which,  however, 
is  quite  readily  available,  and  hence  there  results  a  gain  rather  than  a 
loss.  But  in  case  the  soil  is  deficient  in  lime  and  contains  an  excess 
of  iron  and  aluminum  hydrates  and  silicates,  similar  to  Hawaiian 
soils,  an  entirely  different  problem  is  encountered.  In  this  case  the 
phosphoric  acid  will  be  fixed  by  the  iron  and  aluminum  compounds, 
thus  being  rendered  not  only  practically  insoluble  in  water,  but  also 
in  weak  organic  acid  solvents.  For  such  conditions  various  investi- 
gators recommend  the  application  of  lime  preceding  that  of  the  super- 
phosphate, the  theory  being  that  the  lime  will  revert  the  phosphoric 
acid.  This  theory  has  been  put  in  practice  in  the  red  clay  soils  of 
the  Wahiawa  district  of  Oahu,  but  has  failed  to  produce  any  bene- 
ficial results.  This  is  probably  due  to  the  excessive  amounts  of  iron 
and  aluminum  hydrates  in  these  soils. 

As  indicated  in  the  preceding  tables,  there  is  considerable  difference 
in  the  absorption  of  the  potassium  and  calcium  phosphates.  Since 
they  were  not  carried  to  the  saturation  point,  we  can  only  compare 
the  rates  of  absorption,  and  here  the  fixation  of  calcium  phosphate 
is  strikingly  faster.  It  will  be  seen  that  more  phosphoric  acid  was 
fixed  from  calcium  phosphate  in  two  of  the  soils  and  practically  the 
same  in  the  other  two,  even  though  1  liter  more  of  the  potassium 
phosphate  solution  was  passed  through.  On  the  other  hand,  nearly 
the  same  weight  of  the  salt  has  passed  through,  and  the  general  prop- 
erty of  absorption  is  similar.  In  both  cases  soil  No.  292  fixed  the  least 
phosphoric  acid,  No.  474  next  least,  No.  428  next,  and  No.  448  the  most. 
Both  of  the  soils  that  fixed  the  least  phosphoric  acid  contained  a  high 
percentage  of  phosphoric  acid,  a  sufficiency  of  lime,  and  a  high  percent- 
age of  organic  matter.  It  is  probable  that  reversion  takes  place  more 
quickly  with  the  calcium  salt,  which  accounts  for  the  higher  rate  of 
fixation  in  this  case.  There  appears  to  be  little  correlation  between 
the  rate  of  fixation  and  the  mechanical  composition  of  the  soil  in 
cases  where  the  size  of  the  particles  is  offset  by  the  organic  matter, 
48303°— 14— 2* 


10 

the  highest  and  the  lowest  in  fixing  power  being  both  sandy  soils 
but  differing  in  organic-matter  content.  The  fact  that  the  fixation 
of  phosphoric  acid  from  the  calcium  salt  was  not  excessively  greater 
than  that  from  the  potassium  salt  was  probably  due  to  the  fixation 
being  largely  a  result  of  the  action  of  iron  and  aluminum  compounds 
and  only  a  partial  reversion  of  the  calcium  salt.  Crawley  *  found 
that  upon  irrigating  Hawaiian  soils  immediately  after  application  of 
water-soluble  phosphate  one-half  of  the  phosphoric  acid  remained  in 
the  first  inch  of  soil,  nine-tenths  in  3  inches,  and  practically  all  in  6 
inches  of  the  surface  soil.  These  results  indicate  the  absolute  neces- 
sity of  turning  all  applications  of  phosphate  under  by  deep  plowing 
in  order  to  get  the  best  results.  Otherwise  the  rain  is  not  able  to 
wash  it  down  to  the  roots,  and  consequently  the  dissemination  of 
this  fertilizer  is  incomplete. 

At  the  point  where  these  series  were  stopped  the  soils  had  appar- 
ently lost  none  of  their  fixing  power.  This  fact  lends  very  strong 
proof  to  the  theory  that  the  concentration  of  the  soil  solution  with 
regard  to  phosphoric  acid  is  not  increased  by  the  addition  of  this 
element  in  moderate  quantities  either  as  a  soluble  or  insoluble  salt; 
also,  that  while  there  are  differences  in  the  concentration  of  the  solu- 
'tion  in  different  soils,  they  are  due  to  factors  other  than  the  solubility 
of  the  salt  in  water. 

ABSORPTION  OF  POTASH. 

For  the  study  of  the  absorption  of  potash  a  solution  of  potassium 
sulphate,  containing  about  200  parts  per  million  of  potassium  (K) 
was  used.  The  soils  were  the  same  as  used  in  the  phosphate  series, 
and  the  method  of  percolation  was  through  a  column  of  100  grams  of 
the  soil  placed  in  glass  tubes,  as  already  described.  At  the  outset 
the  solution  percolated  quite  rapidly,  but  after  five  days  much  more 
slowly  in  soils  Nos.  292  and  428,  and  extremely  slowly  in  soil  No. 
448.  A  precipitate,  apparently  of  ferric  hydrate,  formed  upon  stand- 
ing overnight  in  the  extract  from  soil  No.  292.  After  about  one 
month  the  percolation  from  soil  No.  448  (yellow  clay  soil)  became 
so  slow  as  to  be  several  hundred  cubic  centimeters  behind  the  rest 
of  the  series.  However,  strange  to  say,  about  one  week  following 
the  date  of  above  conditions,  the  percolation  in  soil  No.  448  was 
faster  than  with  the  other  soils,  and  when  the  experiments  were 
stopped  soil  No.  474  was  percolating  the  most  slowly  of  all. 

In  order  to  get  a  clear  conception  regarding  the  absorption  of  pot- 
ash, it  is  of  some  value  to  know  the  effect  of  leaching  the  soils  with 
water  upon  the  solubility  of  this  element.  The  table  following 
throws  some  light  upon  this. 

i  Jour.  Amer.  Chem.  Soc,  24  (1902), p.  1114. 


11 


Potash  removed  from  the  soils  by  distilled  water. 
[Expressed  in  parts  per  million  of  K  in  the  percolate. 1 


Percolates  of  100 
cc.  each. 

SoU  No. 
292. 

SoU  No. 
448. 

Soil  No. 
428. 

Soil  No. 
474. 

100 

52 

44 
20 
28 
8 
20 

44 
44 

28 
16 
16 

108 
68 
52 
56 
44 

200 

300 

44 
40 
20 

400 

500 

Thus  it  is  shown  that  the  general  tendency  of  the  soils  was  to  yield 
a  solution  of  fairly  constant  concentration.  However,  attention 
should  be  called  to  the  fact  that  these  figures  do  not  represent  parts 
per  million  in  the  soil,  but  simply  in  the  solution  obtained  through 
percolation. 

The  following  table  shows  the  absorbing  power  of  the  soils  for 
potash,  using  a  solution  containing  214  parts  per  million  of  potassium 
sulphate. 

Absorption  of  potash  from  a  solution  of  KzSO^. 
[Expressed  in  parts  per  mnlion  of  K  in  the  percolate.] 


Percolates  of 

of  100  cc. 

each. 


100.. 
200.. 
300.. 
400.. 
500.. 
600.. 
700.. 
800.. 
900.. 
1,000 
1,100 
1,200 
1,300 
1,400 
1,500 
1,600 
1,700 


Soil  No. 

Soil  No. 

Soil  No. 

Soil  No. 

292. 

448. 

428. 

474. 

60 

52 

48 

100 

52 

92 

56 

80 

40 

80 

40 

76 

64 

100 

52 

84 

76 

140 

124 

104 

56 

148 

152 

88 

60 

160 

156 

96 

72 

164 

188 

84 

76 

188 

192 

88 

76 

168 

192 

76 

64 

168 

212 

72 

84 

196 

192 

84 

136 

208 

200 

84 

96 

204 

204 

104 

120 

172 

200 

116 

128 

160 

204 

140 

124 

160 

196 

160 

Percolates  of 

of  100  cc. 

each. 


1,800. 
1,900 
2,000 
2,100 
2,200 
2,300 
2,400 
2,500 
2,700 
2,900 
3,100 
3,300 
3,500 
3,700 
3,900 
4,100 
4,300 


Soil  No. 

Soil  No. 

Soil  No. 

292. 

448. 

428. 

140 

164 

184 

132 

148 

188 

128 

164 

192 

120 

188 

180 

100 

172 

184 

148 

172 

188 

132 

200 

172 

116 

200 

180 

136 

200 

200 

152 

204 

216 

152 

224 

224 

184 

212 

232 

152 

220 

216 

160 

204 

224 

148 

216 

204 

164 

228 

200 

164 

220 

228 

Soil  No, 
474. 


172 
160 
176 
168 
156 
180 
156 
168 
188 
168 
184 
204 
208 
212 
168 
200 
212 


Summary  of  above  table. 


SoU  No. 

K  added 

tolOOgm. 

soU. 

K  fixed 

by  100 

gm.  soil. 

Per  cent 
ofK 
fixed. 

292 

Gram. 

0.9030 

.9030 

.9030 

.9030 

Gram. 

0. 4030 

.1496 

.2380 

.2782 

45 

448 ; 

17 

428 

26 

474 

31 

In  order  more  easily  to  explain  the  absorption  of  potash  by  soils 
it  is  of  considerable  importance  to  know  the  effect  of  the  addition  of 
potash  upon  the  solubility  of  the  other  bases  commonly  occurring  in 
soils.  For  this  reason  several  determinations  were  made  to  ascer- 
tain the  concentration  of  lime  and  magnesia  in  the  filtrate.  The 
table  followiug  gives  the  results  of  these  determinations. 


12 


Effect  of  the  potassium  sulphate  solution  upon  the  solubility  of  lime  and  magnesia  in  the 

soils. 

[Expressed  in  parts  per  million  in  the  percolate.] 


Percolates  of  100  cc. 
each. 

Lime. 

Magnesia. 

Soil 
No.  292. 

Soil 
No.  448. 

SoU 

No.  428. 

SoU 
No.  474. 

SoU 
No.  292. 

SoU 
No.  448. 

SoU 
No.  428. 

SoU 

No.  474. 

100 

104 
56 
66 
50 
68 
36 
26 

44 
28 
22 
20 
36 
24 
14 

40 
10 
24 
24 
24 
12 
8' 

514 
146 
150 
158 
164 
70 
48 

102 
70 
94 
72 
68 
32 
54 

24 
34 
32 
32 
26 
24 
26 

34 
28 
26 
18 
22 
22 
34 

82 

300 

46 

500 

40 

700 

38 

900 

38 

2,700 

24 

3,300 

34 

The  data  presented  in  the  preceding  tables  throw  considerable  light 
upon  the  retaining  power  which  Hawaiian  soils  possess  for  potash. 
In  the  absorption  of  potash  the  salts  undergo  a  decomposition,  the 
result  of  which  is  a  replacement  of  calcium  or  magnesium  by  potassium. 
The  two  former  elements  combine  with  the  acid  constituent  of  the 
potash  salt  and  pass  off  in  the  drainage  water.  It  has  been  found 
that  potassium  sulphate  is  more  firmly  fixed  than  the  chlorid.  In 
general  the  reaction  taking  place  is  a  replacement  of  the  calcium  in 
the  zeolitic  silicates,  but  humus  and  the  iron  and  aluminum  hydrates 
also  fix  potash  to  a  certain  extent. 

It  may  be  seen  from  the  above  tables  that  the  soil  highest  in  lime 
and  magnesia  had  the  highest  fixing  power  for  potash,  and  the  other 
three  soils  in  proportion.  This  is  in  agreement  with  the  findings 
of  other  investigators.  Crawley  *  found  that  Hawaiian  soils  fixed 
potash  quite  firmly,  but  the  fixation  was  not  nearly  so  lasting  as  that 
of  phosphoric  acid.  The  results  given  herewith  indicate  this  to  be 
true  and  also  the  saturation  point  for  potash  to  be  far  below  that  of 
phosphoric  acid,  even  in  the  soils  high  in  lime  and  magnesia.  In  the 
preceding  table  there  are  some  very  striking  results  showing  the 
decrease  in  concentration  of  lime  and  magnesia  in  the  filtrate,  with 
decrease  in  amount  of  potash  fixed  by  the  soil.  The  fixation  of  this 
element  in  the  soils  highest  in  lime  and  magnesia  is  almost  constant 
for  the  first  liter  of  solution  passing  through  the  soil  column.  On  the 
other  hand,  the  fixing  power  of  the  other  soils  decreases  more  rapidly 
and  they  are  more  easily  saturated,  while  the  soil  containing  8  per 
cent  of  magnesia  had  not  reached  a  state  of  saturation  at  the  close  of 
the  experiments. 

ABSORPTION  OF  NITROGEN. 

AMMONIUM  SULPHATE. 

This  series  was  carried  out  in  a  manner  similar  to  the  previous 
one — namely,  100  grams  of  soil  was  placed  in  glass  tubes,  with  percola- 
tion at  the  rate  of  100  cubic  centimeters  per  24  hours.     The  percolate 

1  Jour.  Amer.  Chem.  Soc,  25  (1903),  p.  47. 


13 


remained  clear  through  the  series,  except  for  a  flocculent  precipitate 
which  appeared  to  be  ferric  hydrate,  and  which  was  deposited  from 
soil  No.  428. 

The   following    table   shows    the    amount    of    ammonia   nitrogen 
removed  from  the  original  soils  by  distilled  water: 

Ammonia  nitrogen  removed  from  the  soils  by  distilled  water. 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

SoU 
No.  292. 

SoU 

No.  448. 

Soil 
.No.  428. 

Soil 
No.  474. 

100 

6.5 
5.7 
2.2 
2.9 

11.4 

8.4 
5.7 
5.7 
5.6 

13.4 

8.8 
5.4 
6.4 
7.3 

4.2 
4.4 
2.3 
3.0 
5.1 

200 

300 

400 

500 

From  these  data  it  may  be  seen  that  these  soils  possess  the  same 
general  tendency  to  produce  a  solution  of  constant  nitrogen  content. 

In  the  following  table  may  be  observed  the  absorbing  power  of 
the  soils  for  nitrogen  in  ammonium  sulphate: 

Absorption  of  nitrogen  from  a  solution  of  (NH4)2  S04. 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 
SOLUTION  USED  CONTAINED  171  PARTS  PER  MILLION  NITROGEN. 


Percolates  of 
100  cc.  each. 

Soil  No. 
292. 

SoU  No. 
448. 

SoU  No. 
428. 

SoU  No. 
474. 

100 

3.6 

2.6 

3.6 

5.6 

12.8 

14.7 

22.8 

15.8 

17.1 

18.7 

46.8 
64.4 
36.8 
39.6 
36.8 
51.5 
51.5 
39.6 
36.8 
42.8 

39.6 
64.4 
34.2 
39,6 
39.6 
51.5 
44.8 
36.8 
36.8 
39.6 

2.6 
2.6 
8.6 
7.4 
2.6 
4.5 
5.4 

12.1 
.12.8 

15.8 

200 

300 

400 

500 

600 

700 

800 

900 

1,000 

Percolates  of 
100  cc.  each. 


1,100 
1,200 
1,300 
1,400 
1,500 
1,600 
1,700 
1,800 
1,900 


Soil  No. 

SoU  No. 

SoU  No. 

292. 

448. 

428. 

21.4 

42.8 

39.6 

51.5 

51.5 

51.5 

51.5 

46.8 

51.5 

51.5 

57.2 

64.4 

51.5 

57.2 

62.9 

68.4 

73.6 

68.4 

64.4 

68.4 

75.2 

64.4 

87.1 

87.1 

86.0 

94.4 

86 

Soil  No. 
474. 


17.1 
46.8 
51.5 
46.8 
51.5 
57.2 
64.4 
73.6 
80.8 


SOLUTION  USED  CONTAINED  168  PARTS  PER  MILLION  NITROGEN. 


2,000 
2,100 
2,200 
2,300 
2,400 
2,500 
2,700 
2,900 


70.8 

73.6 

78.8 

73.6 

76.4 

91.6 

73.6 

73.6 

123.6 

128 

117.9 

96.6 

105.2 

93.3 

117.1 

73.2 

114.1 

128.8 

128.8 

128.8 

121.2 

121.2 

128.8 

121.2 

117 

156.6 

174.2 

143 

156.4 

158.4 

167.8 

140.7 

3,100 
3,300 
3,500 
3,700 
3,900 
4,100 
4,300 
4,500 


119 

126 

134 

117.6 

135.2 

156.8 

186 

163 

138 

156.5 

148.9 

115.6 

152.4 

149.9 

88.8 

152 

152 

120.8 

147.2 

137.6 

120 

164.8 

171.2 

164.8 

112 

124.8 

148 

139.8 

137.6 

141.6 

120 

164.8 


Summary  of  above  table. 


Soil  No. 

Nitrogen 

added  to 

100  gm. 

soil. 

Nitrogen 

fixed  by 

100  gm. 

soU. 

Per  cent 
of  nitro- 
gen fixed. 

2y2 

Gram. 

0.6811 

.6811 

.6811 

.6811 

Gram. 

0. 2782 

.2290 

.2753 

.3015 

41 

448...                                                   

34 

428 

40 

474 

44 

14 

The  nature  of  the  reaction  accompanying  the  absorption  of  am- 
monium compounds  is  very  similar  to  that  of  potash  salts;  namely, 
the  replacing  of  calcium  in  humus,  double  silicates,  and  in  some  cases 
calcium  carbonate.  Hence  the  application  of  ammonium  salts  as 
fertilizer  tends  to  deplete  the  soil  of  its  basic  constituents. 

It  may  be  seen  from  a  comparison  of  the  preceding  tables  that  the 
fixation  of  nitrogen  is  far  in  excess  of  that  of  potash  in  every  instance 
except  soil  No.  292,  which  is  the  highest  in  magnesia  content.  The 
fixing  power  of  the  four  soils  in  the  series  agrees  more  closely  than  in 
the  potash  series,  but  in  each  instance  the  clay  soil  fixed  the  least. 
Attention  is  called  to  soils  Nos.  428,  448,  and  474,  which  absorb  much 
more  nitrogen  than  potash.  In  case  of  two  of  the  soils  (428  and  474) 
this  may  be  accounted  for  by  the  high  content  of  organic  matter. 
In  the  last  two,  fractions  of  percolate  nitrates  and  nitrites  were  de- 
termined and  both  were  found  to  be  present  in  one  case  to  the  extent 
of  14.4  parts  per  million  N  as  N03  and  3.1  parts  per  million  N  as  N02. 
This  indicates  the  rate  at  which  nitrification  was  going  on  at  the  close 
of  the  experiments. 

As  in  the  potash  series,  the  highly  basic  soils  fixed  much  more 
nitrogen  at  the  beginning  of  the  experiments  and  a  much  larger  total 
amount  than  the  less  basic.  On  the  other  hand,  the  decrease  in  fixing 
power  was  much  slower  and  more  gradual  in  the  other  soils. 

SODIUM  NITRATE. 

Of  the  salts  commonly  used  as  fertilizing  materials  all  are  strongly 
fixed  by  the  soil  except  nitrates.  However,  nature  has  made  a  wise 
provision  for  retaining  nitrogen  in  an  insoluble  form,  which  becomes 
slowly  available  for  growing  plants.  Determinations  of  the  amount 
of  nitrate  nitrogen  removed  from  the  original  soils  gave  the  following 
results : 

Nitrate  nitrogen  removed  from  the  soils  by  distilled  water. 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Percolates  of  100  cc.  each. 

Soil 
No.  292. 

Soil 

No.  448. 

Soil 
No.  428. 

Soil 
No.  474. 

100 

4.2 

2.4 

.0 

8.6 
.0 
.0 

5.9 
.0 
.0 

106 

200 

2 

300 

.4 

These  data  indicate  a  condition  found  to  be  true  in  all  soils,  namely, 
the  readiness  with  which  nitrates  are  leached  from  the  soil  by  rains. 
Soil  No.  474  is  a  very  porous,  floury  soil,  containing  a  high  percentage 
of  organic  matter,  and  under  the  existing  climatic  conditions  would 
be  expected  to  have  a  high  nitrate  content. 


15 

The  following  table  shows  the  absorbing  power  of  these  soils  for 
nitrate  nitrogen,  using  a  solution  of  sodium  nitrate  which  contained 
250  parts  per  million  of  nitrogen: 

Absorption  of  nitrogen  from  a  solution  of  NaN03. 
[Expressed  in  parts  per  million  of  nitrogen  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

SoU  No. 
292. 

SoU  No. 
448. 

Soil  No. 
428. 

Soil  No. 
474. 

Percolates  of 
100  cc.  each. 

SoU  No. 
292. 

Soil  No. 

448. 

SoU  No. 
428. 

Soil  No. 
474. 

100 

147 
184 

215 
245 
240 
225 
205 
230 
230 

157 
162 
190 
240 
245 
220 
205 
240 
225 

142 
180 
180 
205 
225 
220 
215 
215 
225 

290 
170 
200 
235 
235 
200 
195 
220 
175 

1,000 

240 
240 
230 
240 
245 
250 
250 
250 
250 

225 
230 
235 
235 
240 
245 
250 
250 
250 

230 
230 
235 
240 
240 
250 
250 
250 

195 

200... 

1,100 

185 

300... 

1,200 

215 

400... 

1,300 

215 

500... 

1,400 

215 

COO... 

1,500 

220 

700 

1,600 

225 

800 

1,700 

900 

1,800 

Summary  of  above  table. 


Soil  No. 

Nitrogen 

added  to 

100  gm. 

sorl. 

Nitrogen 

fixed  by 

100  gm. 

soil. 

Per  cent 
of  nitro- 
gen fixed. 

292 

Gram. 

0.4500 
.4500 
.4250 
.  4000 

Gram. 

0.0384 
.0456 
.0518 
.0610 

8.5 
10 

448 

428 

12 

474 

15 

The  above  table  presents  some  very  interesting  data.  It  is  quite 
generally  conceded  that  soils  have  no  fixing  power  for  nitrates  and 
for  this  reason  it  is  difficult  to  explain  the  action  of  soil  No.  474 
toward  this  salt.  The  percolation  was  very  slow  in  this  instance 
and  the  rate  decreased  to  such  an  extent  that  the  series  had  to  be 
stopped  after  1,600  cubic  centimeters  had  passed  through,  as  the 
solution  would  no  longer  filter  through  the  column.  This  condition 
exists  in  spite  of  the  fact  that  the  soil  contained  only  an  extremely 
small  percentage  of  clay.  Soil  No.  428  acted  somewhat  similarly, 
but  percolation  did  not  stop  completely  as  in  the  case  of  No.  474. 
This  condition  is  undoubtedly  brought  about  by  the  action  of  sodium 
nitrate  upon  the  organic  matter,  as  both  of  these  soils  were  high  in 
this  constituent.  Soil  No.  474  was  apparently  still  fixing  nitrogen 
at  the  close  of  the  experiment,  as  in  no  case  except  with  the  first  100 
cubic  centimeters  did  the  percolate  reach  a  concentration  of  250 
parts  per  million.  These  figures  indicate  that  while  soils  are  unable 
to  retain  nitrates  against  the  action  of  nitrate-free  water,  they  are 
able  to  retain  limited  amounts  against  the  action  of  water  with  a 
high  nitrate  content.  It  is  possible  that  considerable  denitrification 
took  place  in  soil  No.  474.  The  sluggish  movement  of  the  solution 
through  this  soil  indicates  the  existence  of  just  the  conditions  which 
are   conducive   tp   denitrification.     The   same   is   true   of   No.    428. 


16 


Denrtrification  refers,  of  course,  to  any  transformation  which  nitrates 
may  undergo,  such  as  its  conversion  into  nitrate,  ammonia,  free  nitro- 
gen, or  protein. 

ABSORPTION  OF  FERTILIZER  SALTS  BY  FRESH  AND  AIR-DRIED 

SOILS. 

The  type  of  soil  occurring  in  greatest  abundance  on  the  islands  is  a 
highly  ferruginous  red  clay  (No.  517).  For  this  reason  it  was  de- 
cided to  make  a  series  of  percolations  using  both  soil  and  subsoil  of 
this  type  in  the  fresh  and  air-dry  condition,  using  sodium  nitrate, 
ammonium  sulphate,  potassium  phosphate,  and  calcium  phosphate. 

The  fresh  soil  contained  19.7  per  cent  moisture;  the  fresh  subsoil, 
24.4  per  cent  moisture. 

The  method  employed  was  essentially  the  same  as  that  used  in  the 
previous  series  except  that  it  was  found  to  be  necessary  to  use  only  50 
grams  of  soil  with  the  phosphates  in  order  to  effect  a  passage  of  the 
solution  through  the  soil  column.  Also  the  concentration  of  the  solu- 
tion was  increased  in  an  attempt  to  saturate  the  soil  with  phosphates. 
Determinations  were  made  of  the  solubility  in  distilled  water  of  the 
phosphate  in  the  saturated  soil,  and  it  was  found  to  be  negligible. 
On  passing  distilled  water  through  a  column  of  50  grams  of  soil  and 
determining  the  percentage  of  phosphoric  acid  in  each  100  cubic 
centimeters  passing  through,  only  a  faint  trace  was  detected. 

ABSORPTION  OF  PHOSPHORIC  ACID. 

The  following  table  shows  the  absorbing  power  of  the  red  clay  soil 
for  phosphoric  acid  when  applied  as  monopotassium  phosphate: 

Absorption  of  phosphoric  acid  from  a  solution  of  KH2  PO^. 

[Expressed  in  parts  per  million  of  PO4  in  the  percolate.] 
P04  IN  SOLUTION,  800  PARTS  PER  MILLION. 


Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

44 
38 
124 

72 
128 
165 

Trace. 
21 
22 

Trace. 
27 
29 

400 

180 
220 
290 

260 
340 

340 

24 

32 

200 

500 

300 

600 

P04  IN  SOLUTION,  1,400  PARTS  PER  MILLION. 

500.. 
600.. 
700.. 
800.. 
900.. 
1,000. 
1,100. 
1,200. 


410 
390 
400 
430 
530 
620 


460 
460 
500 
500 
400 
560 


150 
325 
350 
560 
675 
825 


290 
325 
360 
665 
675 
825 


1,300. 
1,400. 
1,500. 
1,600. 
1,700. 
1,800. 
1,900. 
2,000. 


950 
900 
750 
750 
725 
875 
675 
875 


850 
825 
750 
750 
600 
850 
675 
825 


P04  IN  SOLUTION,  1,025  PARTS  PER  MILLION. 

1,500 

700 
675 
600 

700 
675 
600 

2,800 

950 

950 

1,750 

3,250.... 

600 

600 

2,250 

3,300... 

1,025 

1,025 

2.500 

750 

675 

675 

675 

3,800 

4,300 

950 
1,025 

950 
1,025 

2,725 

17 

Summary  of  preceding  table. 


Sou. 


P04 

added  to 

100  gm. 

soil. 


PO, 
fixed  by 

100  gm. 
soil. 


Per  cent 
01PO4 
fixed. 


Fresh  soil 

Fresh  subsoil.. 

Air-dry  soil 

Air-dry  subsoil 


Grams. 
9. 5950 
9. 5950 
6.8350 
6.8350 


Grams. 
3.8062 
3.  85 1 1 
2.  7372 
2. 6820 


39.6 
40.2 
40.1 
39.3 


The  absorption  of  phosphoric  acid  from  monocalcium  phosphate 
was  as  follows : 

Absorption  of  phosphoric  acid  from  a  solution  of  Cal^  (POi)2' 

[Expressed  in  parts  per  million  of  PO<  in  the  percolate.] 

SOLUTION  CONTAINED  1,300  PARTS  PER  MILLION  PO4. 


Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

210 
470 
615 

210 
490 
585 

203 
750 
625 

203 
700 
800 

400 

700 

1,012 

925 

650 
1,012 
1,200 

700 

703 

200 

500 

300          

600 

SOLUTION  CONTAINED  1,700  PARTS  PER  MILLION  P04. 


500. 

775 
850 
1,250 
1,000 
1,100 
1,025 
850 
1,300 

775 
850 
1,100 
1,000 
1,250 
1,000 
975 
1,275 

1,300 

1,400 

1,500 

1,600 

1,700 

1,800 

1,900 

1J00 
1,200 
1,350 
1,350 
1,350 
1,250 
925 

1,100 
1,150 
1,400 
1,250 
1,250 
1,325 
925 

600 

700 

1,300 

825 

900 

1,100 

1,100 

950 

1,275 

950 

950 

1,100 

1,100 

950 

800 

900 

1,000 

1,100 

1,200 

SOLUTION  CONTAINED  2,812  PARTS  PER  MILLION  PO4. 


1,700 

1,300 

1,250 
1,250 

2, 750  

3,000 

1,250 

1,925 

2,812 

2,812 

1,950 

1,300 

3,250 

3,500 

1,600 

1,550 

2,000 

1,350 

1,350 

2,812 

2,812 

2,450 

1,600 

3,800 

4,300 

2,812 
2,812 

2,812 
2,812 

2,500 

2,725 

1,450 

1,350 
1,400 

1,600 

Summary  of  above  table. 


Soil. 

PO4  add- 
ed to  100 
gm.  soil. 

PO<  fixed 

by  100 
gm.  soil. 

Per  cent 
of  PO4 
fixed. 

Grams. 
8. 3328 
8.3328 
6.9416 
6.9416 

Grams. 
5.9110 
5. 9880 
5. 5232 
5.  4732 

70.9 

71.8 

79.6 

78.8 

18 

The  results  in  the  above  tables  can  be  compared  with  those  of  the 
previous  series  only  relatively,  due  to  the  fact  that  the  solution  in 
this  case  was  so  much  more  concentrated.  They  indicate  the  prac- 
tical impossibility  of  saturating  Hawaiian  soils  with  phosphoric  acid 
or  adding  an  excess  in  a  practical  way.  It  will  be  noted  that  this 
type  of  soil  is  able  to  absorb  nearly  4  per  cent  of  its  weight  of  phos- 
phoric acid  (P04)  in  the  fresh  soil  and  nearly  3  per  cent  in  the  air-dry 
soil  from  the  potassium  salt;,  also,  that  from  the  calcium  salt  the 
soil  absorbed  nearly  6  per  cent  of  its  own  weight  of  phosphoric  acid 
in  the  fresh  soil  and  5.5  per  cent  in  the  air-dry  soil.  It  is  difficult 
to  explain  the  higher  absorptive  power  of  the  fresh  soil  over  the  air 
dry,  but  it  is  probably  due  to  the  physical  properties,  and  is  related 
to  the  soil  films. 

This  soil  is  composed  of  very  fine  particles,  exposing  relatively 
enormous  surface  to  the  action  of  the  soil  solution  or  any  added  salt 
solution.  In  the  fresh  soils  of  this  type  these  particles  are  in  a  high 
state  of  deflocculation  and  the  effect  of  drying  in  the  air  tends  to 
flocculate  them  to  a  great  extent,  thereby  reducing  the  area  of  the 
exposed  surface.  Drying  would  also  tend  to  modify  the  film  sur- 
rounding each  particle.  Even  with  only  50  grams  of  soil  it  was 
found  impossible,  due  to  the  strong  deflocculating  action  of  the 
phosphate  salts,  to  make  the  percolations  in  tubes,  but  funnels  had 
to  be  used.  The  samples  previously  dried  in  the  air  percolated 
more  slowly  than  the  fresh  soils.  This  is  probably  due  to  the  fact 
that  the  soil  swelled  more  in  the  tube  after  the  addition  of  the  solu- 
tion, thus  packing  more  closely  and  closing  up  the  pore  spaces. 

There  was  apparently  very  little  difference  between  the  absorbing 
power  of  the  soil  and  subsoil,  but  considerable  variation  between 
the  fresh  and  air-dry  soils.  The  rate  of  fixation  in  the  early  part  of 
the  experiment  was  considerably  faster  in  the  latter  than  in  the 
former,  and  hence  the  air-dry  soils  were  more  quickly  saturated  by 
the  salts.  Another  interesting  fact  is  the  difference  in  the  absorp- 
tive power  of  this  type  of  soil  for  phosphoric  acid  in  the  two  forms. 
The  data  are  sufficient  to  justify  the  statement  that  this  difference 
is  due  to  the  reversion  of  the  calcium  salt,  although  due  also  in  great 
part  to  the  state  of  the  iron  and  aluminum  compounds  which  exist 
in  this  type  of  soil.  The  absorption  from  the  potash  salt  was  more 
complete  at  the  first  application,  but  thereafter  decreased  quite 
rapidly  and  regularly.  It  should  also  be  noted  that  at  the  outset 
the  air-dry  soil  absorbed  the  potash  salt  more  completely  than  the 
fresh  soil.  This  is  thought  to  be  due  to  the  partial  elimination  of 
the  film  surrounding  the  soil  particles,  thus  allowing  the  solution  to 
penetrate  more  thoroughly. 


19 


ABSORPTION  OF  POTASH. 

The  strength  of  solution  used  in  the  potash  series  was  the  same  as 
in  the  first  series.  One  hundred-gram  portions  of  soil  were  used. 
The  results  of  extraction  of  the  original  soils  are  given  in  the  follow- 
ing tables: 

Removal  of  potash  from  soil  by  distilled  water. 

[Expressed  in  parts  per  million  of  K  ih  the  percolate.] 


Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

40 

17.4 

56 

32 

14.8 

32 

64 
52 

48 

32 
36 
32 

400 

52 
68 
32 

84 
16 

27 

23 

200 

500 

300 

600 

The  results  of  determinations  of  the  absorption  of  potash  from 
potassium  sulphate  are  given  in  the  following  table : 

Absorption  of  potash  from  a  solution  containing  204  parts  per  million  Kfrom  K2S04. 
[Expressed  in  parts  per  million  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

Percolates  of 
,  100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

64 
68 
212 
216 
164 
172 
192 
180 
184 

52 
44 
136 
160 
168 
180 
180 
180 
196 

52 
80 
104 
180 
180 
180 
172 
184 
192 

68 
24 
60 
120 
120 
120 
140 
180 
180 

1,000 

1,100 

1 ,200. . . 

172 
152 

176 
152 

180 
180 
196 
192 
172 
196 
204 
188 
212 

176 

200 

192 

300 

184 

400 

1,300. 

200 

500 

1,400 

1,500 

1,600 

1,700 

|  1,800. 

200 
200 
216 
20S 

200 
192 
212 
204 

180 

600 

176 

700 

188 

800 

192 

900 

200 

1 

Summary  of  above  table. 


Sofl. 

K  added 

to  100 
gm.  soil. 

K  fixed 

by  100 

gm.  soil. 

Per  cent 
ofK 
fixed. 

Fresh  soil 

Grams. 

0. 34G8 

.3468 

.3672 

.3672 

Grams. 

0.0468 

.0636 

.0528 

.0972 

13.5 

Fresh  subsoil 

18.3 

Air-dry  soil 

14.4 

Air-dry  subsoil 

26.5 

The  effect  of  the  potassium  sulphate  solution  on  the  solubility  of 
lime  and  magnesia  is  shown  in  the  following  table : 

Effect  of  potassium  sulphate  solution  upon  the  solubility  of  lime  and  magnesia. 
[Expressed  in  parts  per  million  in  the  percolate.] 


Percolates  of  100  cc. 
each. 

Lime  (CaO). 

Magnesia  (MgO). 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

300 

600 

1,700 

60 
50 

44 

u 

38 
64 
34 
16 

62 
38 
62 
20 

50 
54 
52 
24 

34 
56 
20 
18 

28 
56 
20 
12 

34 
18 
20 
14 

30 
20 
20 
12 

20 

These  tables  indicate  that  the  potash  in  this  type  of  soil  is  quite 
soluble.  The  fixing  power  of  this  soil  is  far  below  that  of  the  four 
soils  used  in  the  previous  series;  that  is,  the  red  clay  soil  of  the 
islands  is  more  easily  saturated  with  potash  than  the  other  types. 
This  is  partly  due  to  the  low  lime  and  magnesia  content  of  this 
soil.  The  two  series  illustrate  quite  well  the  effect  of  these  bases 
upon  the  fixation  of  potash.  The  figures  in  the  table  on  page  19 
indicate  the  subsoil  to  have  the  power  of  fixing  more  potash  than 
the  soil,  and  that  drying  in  the  air  tends  to  increase  this  power. 

ABSORPTION  OF  NITROGEN. 


AMMONIUM    SULPHATE. 

This  series  was  carried  through  similarly  to  the  previous  ammonium 
sulphate  series.  A  table  showing  the  solubility  in  distilled  water  of 
the  ammonia  nitrogen  in  the  original  soil  is  given  herewith: 

Ammonia  nitrogen  removed  from  the  soil  by  distilled  water. 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Percolates  of  100  cc.  each. 

Fresh 
soU. 

Fresh 
subsoil. 

Air-dry 
soU. 

Air-dry 
subsoU. 

100 

5.1 
Trace. 
Trace. 

Trace. 
Trace. 
Trace 

7.47 

11.16 

Trace. 

5.04 

200 

6.1 

300 

7.2 

This  type  of  soil  is  shown  to  contain  only  small  amounts  of  ammonia 
nitrogen  soluble  in  water,  the  amounts  being  slightly  lower  than  those 
found  in  the  previous  series. 

The  following  table  shows  the  absorbing  power  of  this  soil  for 
ammonium  nitrogen: 

Absorption  of  nitrogen  from  a  solution  of  (NH4)2  S04. 

[Expressed  in  parts  per  mUlion  in  the  percolate.] 
SOLUTION  CONTAINED   246  PARTS   PER   MILLION   NITROGEN   FROM   (NH^SO*. 


Percolates  of 
100  cc.  each. 

Fresh 
soU. 

Fresh 
subsoU. 

Air-dry 
soU. 

Air-dry 
subsoU. 

Percolates  of 
100  cc.  each. 

Fresh 
soU. 

Fresh 
subsoU. 

Air-dry 
soU. 

Air-dry 
subsoU. 

100 

26.5 
65.2 
71.6 
185 
181.3 
211.5 

17.8 
54.9 
66.6 
143 
183.3 
167.4 

12.5 
113.2 
178.2 
162.3 
165.1 
172 

25.2 
111 
145.6 
149. 6 
168.9 
160 

700 

151.3 

192.9 
178.6 
239 
224 

157.1 

178.6 
152.3 
204 
242 

188 
180 
206 
188 
224 

172 

200 

800 

172 

300 

900 

184 

400 

1,000 

184 

500 

1,100.... 

214 

600 

SOLUTION  CONTAINED 

204   PARTS   PER   MILLION   NITROGEN   FROM   (NH4)2SO*. 

1  200 

181.4 
211.6 

182.6 
200 

224 
206 

214 
206 

1,400 

212 

212 

206 

206 

1,300 

21 

Summary  of  preceding  table. 


Soil. 


Fresh  soil 

Fresh  subsoil . . 

Air-dry  soil 

Air-dry  subsoil 


Nitrogen 
added  to 

100  gm. 
soil. 


Gram. 

0.3318 

.3318 

.2706 

.2706 


Nitrogen 

fixed  Dy 

100  gin. 

soil. 


Gram. 

0.1000 

.1164 

.0916 

.1019 


Per  cent 

of 

nitrogen 

fixed. 


30.1 
35 
33.9 
37.6 


Since  ammonium  salts  are  retained  by  the  soil  in  most  respects  by 
the  same  reactions  which  govern  the  absorption  of  potash,  we  would 
expect  the  red  clay  soil  to  have  the  low  absorptive  power  shown  in 
the  above  table,  which  is  less  than  one-half  that  of  the  soils  used  in 
the  previous  series.  The  subsoil  showed  a  slightly  higher  fixing 
power  than  the  soil,  while  the  effect  of  drying  in  the  air  was  to  reduce 
the  fixing  power.  This  latter  rinding  is  just  the  reverse  of  that 
obtained  in  case  of  potash. 

SODIUM    NITRATE. 


The  absorbing  power  of  this  soil  for  sodium  nitrate  is  very  much 
lower  than  that  of  the  other  types,  as  may  be  seen  from  the  following 
tables : 

Removal  of  nitrate  nitrogen  from  soil  by  distilled  water. 
[Expressed  in  parts  per  million  of  nitrogen  in  the  percolate.] 


Percolates  of  100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry 
subsoil. 

100 

19.2              8.8 

12.8 

7.2 

200 

1 

Absorption  of  nitrogen  from  a  solution  of  250  parts  per  million  nitrogen  from  NaNOz. 
[Expressed  in  parts  per  million  of  nitrogen  in  the  filtrate.] 


Percolates  of  ! 
100  cc.  each. 

Fresh 
soil. 

Fresh 
subsoil. 

Air-dry 
soil. 

Air-dry  1 
subsoil. 

Percolates  of 
100  cc.  each. 

Fresh 
sofl. 

Fresh 
subsoil. 

Air-dry  !  Air-dry 
soil.       subsoil. 

100 

187.5 
250 

180.0 

255 

215.0 
240 

215.0 
240 

300 

250.0 
250 

250.0 
250 

250.0           250.0 

200 

1 

400 

2.50              250 

Summary  of  above  table. 


Soil. 


Nitrogen  Nitrogen 

added  to  fixed  bv 

100  gm.  100  gm". 

soil.  soil. 


Per  cent 

of 

nitrogen 

fixed. 


Gram.  Gram. 

Fresh  soil 0. 1000  0. 0062 

Fresh  subsoil 1000  .  0065 

Air-dry  soil 1000  .  0045 

Air-dry  subsoil 1000  .  0045 


6.2 
6.5 
4.5 
4.5 


22 

The  above  results  show  the  low  fixing  power  of  this  type  of  soil 
for  nitrates.  This  fact  strongly  indicates  the  r61e  of  organic  matter 
in  the  absorption  of  this  salt.  The  organic  matter  content  of  the 
previous  series  of  soils  was  much  higher  than  that  of  the  red  clay. 
There  was  apparently  no  difference  between  the  fixing  power  of  the 
soil  and  the  subsoil,  but  it  was  stronger  in  the  fresh  than  in  the  air- 
dried  samples. 

ABSORPTION  OF  FERTILIZER  SALTS  WHEN  APPLIED  IN  MIX- 
TURES, AND  THE  EFFECT  OF  HEAT  AND  ANTISEPTICS. 

A  third  series  of  experiments  was  made  with  the  idea  in  mind  of 
applying  a  solution  containing  a  mixture  of  fertilizer  salts  and  at  the 
same  time  determining  the  effect  of  heat  and  volatile  antiseptics 
upon  the  absorbing  power.  The  soils  chosen  for  this  series  were  No. 
428,  a  highly  organic  soil  used  in  the  first  series,  and  No.  517,  the  red 
clay  soil  used  in  the  second  series.  Three  fertilizer  mixtures  were 
used  and  applied  to  the  soil  in  series  of  three,  namely,  untreated, 
heated  (230°  C.  in  air  bath),  and  partially  sterilized  (5  cubic  centi- 
meters chloroform  to  100  grams  soil  kept  in  a  closed  fruit  jar  48 
hours,  then  spread  out  in  the  air  24  hours  before  placing  in  the  glass 
tubes).  The  mixtures  were  as  follows:  (1)  ammonium  sulphate, 
potassium  phosphate,  and  potassium  sulphate;  (2)  ammonium 
sulphate,  calcium  phosphate,  and  potassium  sulphate;  and  (3) 
sodium  nitrate,  calcium  phosphate,  and  potassium  sulphate.  The 
solutions  were  allowed  to  percolate  through  the  soil  at  the  rate  of  100 
cubic  centimeters  in  24  hours,  and  the  percolates  were  analyzed. 

ABSORPTION  OF  PHOSPHORIC  ACID. 

The  table  following  shows  the  fixing  power  of  these  soils  for  phos- 
phoric acid  when  applied  in  mixtures. 


23 

Absorption  of  calcium  and  potassium  phosphate  in  solutions  of  fertilizer  mixtures. 
[Expressed  in  parts  per  million  of  PO<  in  the  percolate.] 


Percolates  of  100  cc. 


100.. 
200.. 
300.. 
500.. 
700.. 
900.. 
1,100 
1,300. 
1,500. 
1,700. 
1,900. 
2,100. 


Soil  No.  517. 


Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 


Untreat- 
ed. 

Heated,  j 

Trace. 

46 

86 

34 

140 

22 

200 

70 

480 

360 

168 

Trace. 

480 

420 

480 

460 

540 

540 

480 

500 

580 

640 

560 

560 

form. 


26 
34 
100 
240 
460 
200 
540 
540 
680 
500 
640 
660 


Ammonium  sulphate,  cal- 
cium phosphate,  and 
potassium  sulphate. 


Sodium  nitrate,  calcium 
phosphate,  and  potas- 
sium sulphate. 


Untreat- 
ed. 

Heated. 

26 

38 

50 

120 

392 

512 

550 

650 

1,700 

1,550 

1,600 

1,700 

1,750 

1,750 

1,600 

1,650 

1,700 

1,750 

1,500 

1,800 

1,950 

1,950 

1,950 

2,000 

Chloro- 
form. 


Untreat 
ed. 


44 

380 

448  i 

700 

1,750  : 

1,650 

2,000 

1,850 

1,750 

1,700 

2,000 

2,000 


224 

360 

232 

600 

1,050 

1,400 

1,400 

1,350 

1,250 

1,500 


Heated. 


50 

56 

328 

550 

1,050 

1,350 

1,050 

1,100 

1,500 

1,150 


Chloro- 
form. 


280 

400 

256 

750 

1,050 

1,350 

1,450 

1,400 

1,550 

1,150 


SUMMARY. 


P04  added  to  100 
grams  soil,  grams. 

POi  fixed  by  100 
grams  soil,  grams. 

Per  cent  of  PO*  fixed 


1.5750 

1.5750 

1.5750 

4.3050 

4.3050 

4.3050 

2.8050 

2.8050 

.7588 
48.2 

.8548 
54.3 

.6670 
42.3 

1.  3982 
32.5 

1.2780 
29.7 

1.0678 
24.7 

1.6134 

57.3 

1.2116 
43.2 

2.8050 


1.5014 
53. 5 


Soil  No.  428. 


Percolates  of  100  cc. 


100.. 
200.. 
300.. 
500.. 
700.. 
900.. 
1,100 
1,300 
1,500 
1,700 
1,900 
2,100 


Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 


Untreat- 
ed. 


Trace. 
16 
16 
12 
33 
19 
19 
18 
7 
11 
22 
31 


20 

13 

13 

12 

16 

9 

90 

236 

236 

264 

240 

320 


Chloro- 
form. 


Trace. 
20 
20 
12 
15 
14 
19 
20 
6 
21 
21 
16 


Ammonium  sulphate,  cal- 
cium phosphate,  and 
potassium  sulphate. 


Untreat- 
ed. 

Heated. 

19 

15 

16 

15 

16 

15 

11 

10 

16 

8 

21 

36 

6 

6 

8 

19 

6 

15 

9 

33 

17 

36 

13 

70 

Chloro- 
form. 


Trace. 
15 
15 
11 
15 


Sodium  nitrate,  calcium 
phosphate,  and  potas- 
sium sulphate. 


Untreat- 
ed. 


Heated. 


Chloro- 
form. 


SUMMARY. 


P04  added  to  100 

grams  soil,  grams. 
P04  fixed   bv   100 

1.4700 

1.4700 

1.4700 

0. 8265 

0.8265 

0.8265 

0.6375 

0.6375 

0.6375 

grams  soil,  grams. 
Per  cent  of  PO<  fixed 

1.4296 

1. 1104 

1.4298 

.7995 

.  7754 

.8033 

.61.78 

.6191 

.6161 

97.1 

75.5 

97.1 

9R.8 

93.9 

97.3 

96.9 

97.3 

96.7 

24 

The  solution  used  in  the  first  series  of  three,  columns  1,  2,  and  3 
contained  750  parts  per  million  P04  from  potassium  phosphate;  4,  5, 
and  6,  2,050  parts  per  million  P04  from  calcium  phosphate;  7,  8,  and 
9, 1,650  parts  per  million  P04  from  calcium  phosphate;  10, 11,  and  12, 
700  parts  per  million  P04  from  potassium  phosphate;  13,  14,  and  15, 
435  parts  per  million  P04  from  calcium  phosphate;  16, 17,  and  18,  425 
parts  per  million  P04  from  calcium  phosphate.  The  solution  used 
with  soil  No.  428  was  made  up  to  a  much  weaker  strength  for  the 
reason  that  it  would  be  more  comparable  with  the  results  obtained 
on  this  soil  given  in  the  first  series. 

The  absorbing  power  of  the  red  clay  soil  was  appreciably  less  for 
phosphates  in  mixtures,  but  that  of  the  highly  organic  soil  is  very 
much  the  same,  regardless  of  method  of  application.  The  effect  of 
heat  or  antiseptics  was  not  striking,  but  in  most  instances  caused  a 
decrease  in  the  fixing  power.  In  one  instance,  namely,  with  the 
highly  organic  soil,  the  heat  caused  a  decided  decrease  in  fixing 
power. 

ABSORPTION   OP   POTASH. 

The  results  obtained  with  the  application  of  potash  in  mixtures 
are  shown  in  the  following  table : 


Absorption  of  potash  from  a  solution  of  fertilizer  mixtures. 
[Expressed  in  parts  per  million  K  in  the  percolate.] 


Percolates   100  cc. 
each. 


SoU  No.  517 


Ammonium  sulphate,  po-  Ammonium  sulphate,  cal- 
tassium  phosphate,  and  I  cium  phosphate,  and 
potassium  sulphate.  potassium  sulphate. 


Untreat- 
ed. 


Heated. 


Chloro- 
form. 


Untreat- 
ed. 


Heated, 


Chloro- 
form. 


Sodium  nitrate,  calcium 
phosphate,  and  potas- 
sium sulphate. 


Untreat- 
ed. 


Heated. 


Chloro- 
form. 


100.. 
200.. 
300.. 
500.. 
700.. 
900.. 
1,100. 
1,300. 
1,500. 
1,700. 
1,900. 
2,100. 


196 
348 
440 
484 
544 
540 
540 
564 
544 
544 
488 
428 


180 
316 
440 
460 
508 
580 
584 
576 
560 
576 
564 
528 


268 
300 
376 
480 
552 
524 
572 
588 
504 
528 
544 
496 


172 
152 

44 


164 
124 
184 
156 
152 
196 
164 


120 
132 
80 
84 
224 
260 
216 
288 
224 
244 
188 
192 


156 

88 

72 

64 

228 

276 

200 

204 

176 

140 

216 

184 


108 
104 
176 
84 
216 
204 
180 
256 
228 
156 
284 
212 


112 
132 
104 
120 
232 
228 
188 
180 
236 
360 


144 
108 
68 
108 
140 
208 
232 
132 
172 
280 
288 
248 


SUMMARY. 


K  added  to  100  grams 
soil grams.. 

K  fixed  by  100  grams 
soil grams. 

1.0038 

1.0038 

1.0038 

0. 3570 

0. 3570 

0. 3570 

0.4536 

0.  4536 

0. 4536 

Per  cent  of  K  fixed . 

25 


Absorption  of  potash  from  a  solution  of  fertilizer  mixtures — Continued. 


Soil  No.  428. 

Percolates  of  100  cc. 
each. 

Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 

Ammonium  sulphate,  cal- 
cium   phosphate,     and 
potassium  sulphate. 

Sodium    nitrate,    calcium 
phosphate,    and     potas- 
sium sulphate. 

Untreat- 
ed. 

Heated. 

Chloro- 
form. 

Untreat- 
ed. 

Heated. 

Chloro- 
form. 

Untreat- 
ed. 

Heated. 

268 
192 
224 
240 
•    228 
220 
228 
200 
292 

Chloro- 
form. 

100 

96 
168 

432 

432 
520 
516 
552 
572 
608 
620 
580 
620 
600 
524 

112 
192 
292 
400 
428 
432 
412 
424 
408 
460 
448 
448 

96 
104 
144 
212 
216 
184 
224 
212 
232 
212 
228 
224 

272 
192 
188 
220 
268 
224 
224 
180 
200 
220 
212 
236 

118 
104 
140 
192 
248 
196 
216 

148 
76 
112 

192 
204 
192 
188 

104 

200 

72 

300 

500 

700 

900 

1,100 

300 
360 
416 
420 
368 
416 
416 

112 

180 
188 
216 
188 

1,300 

1,500 

180             188 
192             240 

192 
252 

1,700 

456 
424 
432 

224 
200 
236 

1,900 

2,100 



SUMMARY. 


K  added  to  lOOgrams 

soil grams. . 

K  fixed  bv  lOOgrams 

1.2264 

.  9468 
77.6 

1. 2264 

1. 2264 

1. 0224 
83.6 

: 

0.3822 

0. 3822 

0. 3822 

0.3090 

0.3090 

0.3090 

Per  cent  of  K  fixed. 

1 





The  above  table  presents  some  striking  results,  and  indicates  that 
Hawaiian  soils  possess  a  very  low  fixing  power  for  potash  when 
applied  with  phosphates,  especially  calcium  phosphate.  In  every 
instance,  except  two,  the  amount  of  potash  found  in  the  filtrate  was 
greater  than  the  weight  added  to  the  soil.  This  is  undoubtedly  due 
partly  to  a  replacement  of  the  potash  by  lime.  The  effect  of  heat  in 
case  of  the  highly  organic  soil  was  to  considerably  reduce  the  fixing 
power,  but  chloroform  reduced  it  only  slightly.  With  the  red  clay 
soil  there  was  very  little  variation,  due  to  sterilization  either  with 
heat  or  antiseptics.  This  was  contrary  to  the  results  obtained  when 
potash  was  used  alone.     Drying  in  the  air  increased  the  fixing  power. 

The  solutions  used  on  samples  reported  in  columns  1,  2,  and  3 
contained  478  parts  per  million  K  from  K2S04;  4,  5,  and  6,  170  parts 
per  million;  7,  8,  and  9,  216  parts  per  million;  10,  11,  and  12,  584  parts 
per  million;  13,  14,  and  15,  182  parts  per  million;  16,  17,  and  18,  206 
parts  per  million. 


26 

ABSORPTION  OF  NITROGEN. 
AMMONIUM    SULPHATE. 

The  following  table  shows  the  results  obtained  by  the  application 
of  ammonium  sulphate  in  mixtures: 

Absorption  of  nitrogen  from  a  solution  of  ammonium  sulphate  in  a  mixed  fertilizer. 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Soil  No.  517. 

Percolates  of  100  cc.  each. 

Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 

Ammonium  sulphate,  cal- 
cium   phosphate,    and 
potassium  sulphate. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

100 

81,5 
128.8 

99 
130 
131 
137 
149 
178 
178 
172 

188.4 

148.6 

138 

133 

130 

174 

141 

166 

178 

172 

88.9 

64.9 
125.4 
135 
148 
168 
156 
153 
175 
159 
172 

133.9 

167.2 

114 

143 

128 

159 

151 

170 

159 

172 

91.3 

200 

168.7 

30 

111 
128 
129 
136 
151 
178 
178 
172 

114 

500 

153 

700 

136 

900 

156 

1,100 

164 

1,300 

163 

1,500 

172 

1,700 

172 

1,900 

SUMMARY. 


Nitrogen  added  to  100  grams  soil gram . 

Nitrogen  fixed  by  100  grams  soil do . . . 

Per  cent  of  nitrogen  fixed 


0 

1892 

0. 1892 

0. 1892 

0. 1892 

0. 1892 

0342 

.0152 

.0350 

.0268 

.0194 

IS 

1 

8.03 

18.5 

14.2 

10.2 

0. 1892 
.0231 
12.2 


SoU  No.  428. 

Percolates  of  100  cc.  each. 

Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 

Ammonium  sulphate,  cal- 
cium   phosphate,    and 
potassium  sulphate. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

100 

66.2 

88.2 

89 
109 
120 
103 

90 
118 
147 
147 
172 

154.5 

116.9 

112 

109 

136 

116 

139 

157 

172 

172 

187 

44.9 
103.6 

93 
103 
107 
110 
114 
147 
159 
147 
172 

86.1 
108 
110 
123 
118 
149 
148 
176 
187 
172 
187 

140.7 
.128 
122 
154 
133 
146 
134 
162 
172 
172 
187 

81.5 

200 

112 

300 

107 

500 

116 

700 

112 

900 

122 

1,100 ...                                     

144 

1,300 

145 

1,500 

178 

1,700 

172 

1,900 

187 

SUMMARY. 


Nitrogen  added  to  100  grams  soil. 
Nitrogen  fixed  by  100  grams  soil. 
Per  cent  of  nitrogen  fixed 


.do. 


0. 2064 

0.2064 

0. 2064 

0. 2064 

0.2064 

.0668 

.0322 

.0618 

.0358 

.0257 

32.4 

15.6 

29.9 

17.3 

12.  6 

0.2064 
.  0437 
21.2 


27 

The  veiy  concordant  results  in  the  above  table  add  proof  to  the 
theory  that  the  fixation  of  ammonium  nitrogen  and  potash  are 
strikingly  similar.  The  fixing  power  of  the  soils  was  far  less  for 
the  nitrogen  of  ammonium  sulphate  in  mixtures  than  when  used 
alone.  It  was  found  that  the  heat  decreased  the  fixing  power  of  the 
soil  greatly,  while  chloroform  had  a  very  slight  effect. 

All  solutions  used  in  this  series  contained  172  parts  per  million 
nitrogen  from  ammonium  sulphate. 

SODIUM    NITRATE. 

The  following  table  gives  the  results  of  applying  sodium  nitrate  in 
mixtures : 

Absorption  of  nitrogen  from  a  solution  of  sodium  nitrate  in  a  mixtd  fertilizer . 
[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Soil  No.  517.                                 Soil  No.  428. 

Percolates  of  100  cc.  each. 

Sodium  nitrate,  calcium  phos- 
phate, and  potassium  sul- 
phate. 

Sodium  nitrate,  calcium  phos- 
phate, and  potassium  sul- 
phate. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

100 

225 
210 
210 
165 
215 

220 
210 
215 
210 
215 

245 
200 
200 
170 

215 

190 
160 
175 
190 
215 

190 
215 
220 
225 
215 

185 

200 

no 

300 

145 

500 

220 

700 

215 

SUMMARY. 


Nitrogen  added  to  100  grams  soil. .  .gram. 

Nitrogen  fixed  by  100  grams  soil do. . . 

Per  cent  of  nitrogen  fixed 


0. 1075 

0.1075 

0.1075 

0.1075 

0. 1075 

.0060 

.0010 

.0085 

.0145 

.0010 

5.6 

0.9 

7.9 

13.5 

0.9 

0. 1075 
.0200 
18.6 


The  solutions  used  contained  215  parts  per  million  nitrogen  from 
nitrates,  and,  as  was  to  be  expected,  the  soils  absorbed  only  extremely 
small  amounts.  The  fixing  power  was  shown  to  be  very  much  less 
when  this  salt  was  applied  in  mixtures  than  when  applied  alone, 
the  effect  of  heat  was  to  decrease  the  fixing  power,  while  the  effect 
of  chloroform  was  to  produce  a  decided  increase  in  fixing  power. 
The  latter  is  probably  due  to  the  sterilizing  effect  of  the  antiseptic 
upon  the  organisms  present. 

REMOVAL  OF  ABSORBED   SALTS. 

At  the  conclusion  of  the  preceding  series  distilled  water  was 
allowed  to  percolate  through  the  tubes  at  the  rate  of  100  cubic  centi- 
meters in  24  hours.  In  eveiy  100  cubic  centimeters  of  the  solution 
after  the  first  thus  obtained  phosphoric  acid,  potash,  and  nitrogen 
were  determined. 


28 


REMOVAL  OF  ABSORBED  PHOSPHATE. 

In  the  following  table  will  be  found  the  results  showing  removal  of 
absorbed  phosphoric  acid  by  distilled  water  from  soil  No.  517: 

Absorbed  phosphoric  acid  removed  from  soil. 
[Expressed  in  parts  per  million  PO<  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 

Ammonium  sulphate,  cal- 
cium    phosphate,    and 
potassium  sulphate. 

Sodium    nitrate,    calcium 
phosphate,    and     potas- 
sium sulphate. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

200 

425 
350 
^550 
425 
325 
300 
145 
115 
140 
44 
36 

425 
350 
425 
350 
400 
375 
125 
100 
110 
96 
64 

375 
250 
450 
475 
400 
425 
100 
100 
100 
96 
64 

625 
525 
700 

500 
325 

650 

625 

400 
700 
825 
200 
350 
140 
120 
120 
96 
82 

425 
300 
525 
475 
300 
300 
390 
120 
120 
96 
82 

500 
350 
500 
525 
300 
300 
160 
145 
100 
96 
82 

550 

300 

325 

400 

650 

500 

475            475 

600 

325 
450 
150 
135 
110 
96 
88 

325 
350 
135 
120 
-  120 
96 
88 

300 

700 

300 

800 

190 

900 

125 

1,000 

110 

1,100 

96 

1,200 

82 

SUMMARY. 

0. 7588 
.2855 

0.8548 
.2820 

0. 6670 
.2835 

1. 3982 
.3679 

1.278 
.3184 

1.0678 
.3658 

1.6134 
.3133 

1.2116 
.3058 

37.7 

33.1 

42.4 

26.4 

25. 

34.1 

19.4 

25.2 

P04fixed gm.. 

P04removed..gm.. 
Per  cent  of  P04  re- 
moved    37.7 


1.5014 


20.0 


The  above  results  show  that  the  concentration  of  phosphate  in 
the  percolate  decreased  quite  rapidly,  approaching  a  constant.  Ap- 
parently the  potash  salt  was  less  strongly  fixed  as  the  precentage  re- 
moved is  greater  than  the  calcium  salt. 

REMOVAL  OF  ABSORBED  POTASH. 

In  the  following  table  will  be  found  the  results  showing  removal 
of  absorbed  potash  by  distilled  water  from  soil  No.  517: 

Removal  of  absorbed  potash. 
[Expressed  in  parts  per  million  K  in  the  percolate.] 


Percolates  of 
100  cc.  each. 

Ammonium  sulphate,  po- 
tassium phosphate,  and 
potassium  sulphate. 

Ammonium  sulphate,  cal- 
cium   phosphate,    and 
potassium  sulphate. 

Sodium    nitrate,    calcium 
phosphate,    and    potas- 
sium sulphate. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

Un- 
treated. 

Heated. 

Chloro- 
form. 

200 

204 
115 
112 
108 
96 
96 
72 
76 
76 
48 
68 

56 
84 
80 
72 
52 
84 
52 
72 
48 
44 
68 

108 
96 

104 
96 
68 
92 
68 
64 
56 
60 
68 

48 
36 
40 
40 
16 
52 
28 
40 
32 
20 
24 

44 
32 
44 
32 
16 
40 
48 
56 
40 
40 
32 

32 
48 
40 
48 
16 
32 

44 
36 
40 
68 
20 
36 

60 
56 
56 
44 
32 
44 

44 

300 

40 

400 

36 

500 

52 

600 

20 

700 

36 

800.  .    , 

28 

900 

44 
16 
16 

24 

36 
12 
20 
32 

44 
28 
24 
32 

32 

1,000 

20 

1,100 

20 

1,200 

20 

SUMMARY. 


K  removed gm. 


0. 1072 


0.0712 


0. 0S80 


0. 0376 


0. 0424 


0. 0316 


0.0344 


0. 0420         0. 0348 


29 

The  above  table  adds  further  proof  toward  indicating  the  small 
amounts  of  potash  absorbed  by  this  type  of  soil  when  added  in  mix- 
tures. (See  also  p.  25.)  There  is  little  decrease  in  concentration  of 
the  percolate  with  regard  to  this  element. 

REMOVAL  OF  ABSORBED  NITROGEN. 

In  the  following  table  will  be  found  the  results  showing  removal 
by  distilled  water  of  nitrogen  absorbed  from  ammonium  sulphate 
from  soil  No.  517: 

Removal  of  absorbed  nitrogen. 

[Expressed  in  parts  per  million  nitrogen  in  the  percolate.] 


Percolates  of  100  cc.  each. 

Ammonium   sulphate,    potas- 
sium phosphate,  and  potas- 
sium sulphate. 

Ammonium  sulphate,  calcium 
phosphate,  and  potassium  sul- 
phate. 

Untreated. 

Heated. 

Chloro- 
form. 

Untreated. 

Heated. 

Chloro- 
form. ■ 

200    

73 
51 
46 
42 
31 
25 
21 
16 
21 
21 
13 

68 
44 
39 
30 
20 
17 
16 
16 
16 
16 
16 

66 
44 
42 
33 
22 
22 
18 
16 
21 
18 
11 

84 
46 
28 
18 
7 
7 
4 
3 
11 
3 
2 

73 

38 

25 

13 

9 

7 

6 

5 

9 

4 

4 

73 

300 

40 

400 

22 

500 

10 

600 

700  ..              

3 

800 

3 

900 

3 

1,000 

6 

1,100 

2 

1,200 

2 

SUMMARY. 


Nitrogen  fixed gm. . 

Nitrogen  removed gm. . 

Per  cent  of  nitrogen  removed 


0.0342 
.0360 


0. 0152 
.0298 


0. 0350 
.  0313 
39.5 


0. 0268 
.  0213 
79.6 


0. 0194 
.0193 
99.4 


0. 0231 
.0164 
71.0 


The  above  table  discloses  the  peculiar  fact  that  practically  all  the 
nitrogen  fixed  by  the  soil  from  ammonium  sulphate  was  removed  by 
passing  a  liter  of  water  through  it.  The  concentration  of  the  solu- 
tion tended  to  decrease  toward  a  constant  value,  as  was  the  case  with 
all  the  other  elements  of  plant  food. 


SUMMARY. 

The  data  presented  in  the  foregoing  pages  throw  considerable 
light  upon  the  behavior  of  fertilizer  salts  in  Hawaiian  soils.  They 
show  the  variation  in  absorbing  power  with  the  variation  in  soil  types 
and  composition  of  fertilizer  added.  Hawaiian  soils  have  resulted 
from  the  degradation  of  lava  rocks,  some  of  which  have  subsequently 
been  changed  through  the  addition  of  coral  limestone  or  submergence 
by  the  sea.  Therefore  they  would  naturally  be  expected  to  be  of  a 
highly  basic  nature,  and  to  yield  a  highly  basic  soil  solution,  depending 
upon  the  absorptive  power  of  the  soil.     Some  of  the  soils  have  been 


30 

subjected  to  dense  tropical  plant  growth,  resulting  in  the  accumula- 
tion of  high  percentages  of  humus,  which  has  been  shown  in  the 
previous  tables  to  affect  materially  the  absorbing  power.  Further- 
more, the  data  indicate  that  the  concentration  of  the  soil  solution 
does  not  depend  primarily  upon  the  solubility  of  the  mineral  con- 
stituents, nor  the  amount  of  fertilizer  added,  but  upon  the  absorbing 
power  of  the  soil. 

As  was  expected,  the  fixation  of  phosphoric  acid  was  much  higher 
than  the  other  elements.  This  is  due  to  the  highly  basic  character  of 
the  soils,  and  especially  to  the  large  amounts  of  iron,  aluminum, 
and  titanium  present.  It  has  been  found  in  recent  pot  experiments 
with  this  type  of  soil  that  crops  respond  most  readily  to  soluble 
phosphates — namely,  sodium  phosphate  and  acid  phosphate.  There 
was  considerable  difference  in  the  physical  action  of  calcium  and  po- 
tassium phosphates,  the  latter  having  a  decided  deflocculating  action 
upon  the  clay,  while  the  calcium  salt  filtered  through  the  soil  column 
perfectly  clear.  This,  coupled  with  the  results  of  the  pot  experi- 
ments cited  above,  indicates  that  absorbed  sodium  and  potassium 
phosphates  are  not  insoluble,  but  diffuse  more  readily  and  are  more 
easily  available  for  the  growing  plants.  This  indicates  that  phos- 
phate should  be  applied  to  Hawaiian  soils  in  the  soluble  form,  and 
the  best  time  for  application  is  just  before  planting,  not  on  account 
of  any  danger  of  loss  through  drainage,  but  through  the  danger  of  a 
slight  decrease  in  availability,  due  to  reversion. 

Apparently  the  controlling  factors  in  the  fixation  of  potash  are  the 
amounts  of  lime  and  magnesia  present.  This  is  very  clearly  shown 
in  the  above  tables,  and  the  soils  used  in  the  experiments  were  good 
examples  with  which  to  illustrate  this  point.  The  fixing  power  for 
this  element,  while  not  so  strong  as  for  the  phosphoric  acid,  is  quite 
marked.  However,  it  should  not  be  applied  in  too  large  quantities, 
nor  too  often,  as  it  is  quite  readily  leached  from  the  soil  by  rains  and 
irrigation. 

The  fixation  of  ammonium  nitrogen,  as  already  mentioned,  is  con- 
trolled by  the  same  general  factors  which  govern  the  absorption  of 
potash.  But  the  point  of  saturation  is  in  most  cases  above  that  of  the 
potash.  However,  it  is  not  so  strongly  fixed  and  is  leached  out  quite 
readily  by  the  rains  and  drainage  water.  Some  investigators  claim 
that  ammonia  replaces  the  bases  combined  with  the  complex  "hu- 
mates,"  and,  if  so,  this  accounts  for  the  soils  in  the  first  series  having 
such  a  high  fixing  power  both  for  potash  and  ammonium  nitrogen, 
while  the  red  clay  soil  was  strikingly  lower. 

The  power  of  the  soil  for  fixing  nitrate  nitrogen  is  almost  negligible, 
except  in  case  of  the  highly  organic  soils.     Apparently  the  organic 


31 

matter  reacted  with  the  nitrate  solution,  as  the  effect  of  this  solution 
on  the  soil  was  quite  marked. 

The  series  showing  the  relation  of  the  fixing  power  of  soil  and  sub- 
soil, and  the  effect  of  drying  in  the  air,  gave  only  slight  differences. 
It  was  found,  however,  that  phosphoric  acid  was  fixed  more  strongly 
by  the  fresh  soil,  but  there  was  scarcely  any  difference  between  the 
soil  and  subsoil.  This  is  probably  due  to  the  fact  that  there  is  little, 
if  any,  difference  in  the  mechanical  condition  of  soil  and  subsoil  in 
this  red  clay  type,  and  also  very  little  difference  in  chemical  compo- 
sition. The  fixation  of  potash  was  higher  in  the  air-dried  soil,  as 
previously  explained,  and  higher  in  the  subsoil  than  the  soil.  The 
ammonium  nitrogen,  strange  to  say,  unlike  the  potash,  was  more 
strongly  fixed  by  the  fresh  soil,  which  indicates  the  possibility  of  cer- 
tain organisms  affecting  the  fixation.  The  subsoil  had  a  higher  fixing 
power  than  the  soil.  There  probably  are  also  organisms  acting  as 
fixing  agents  for  the  nitrates,  as  the  fresh  samples  had  a  higher  fixing 
power  than  the  air  dry,  while  there  was  no  difference  in  that  of  the 
soil  and  subsoil. 

The  most  striking  results  are  those  obtained  from  the  series  in  which 
a  solution  of  mixed  fertilizer  was  used.  From  the  data  at  hand  the 
conclusion  is  thought  justified  that  the  least  waste  is  to  be  had  by 
application  of  fertilizer  salts  singly  rather  than  in  mixtures.  When 
the  salts  were  applied  singly  there  was  a  marked  loss  of  potash,  a 
decrease  in  amount  of  ammonium  nitrogen  fixed,  a  decrease  in  nitrate 
nitrogen,  and  a  decrease  in  phosphates  in  case  of  the  red  clay,  but 
scarcely  any  difference  with  the  organic  soil.  However,  there  was  no 
deflocculation  of  the  soil  when  the  salts  were  added  in  mixtures,  except 
to  a  small  extent  in  the  mixtures  which  contained  potassium  phos- 
phate. In  this  instance  the  percolates  came  through  cloudy — that 
is,  they  contained  deflocculated  clay.  On  the  other  hand,  the  extracts 
in  which  the  calcium  salt  was  used  were  perfectly  clear  and  colorless. 
Again,  all  the  percolations  proceeded  quite  rapidly,  while  several  of 
the  salts,  the  phosphates  in  particular,  when  used  alone,  would  not 
allow  a  solution  to  pass  through  a  column  of  soil.  Solutions  contain- 
ing potassium  phosphate  percolated  more  slowly  than  those  contain- 
ing calcium  phosphate. 

The  effect  of  heat  and  antiseptics  was  not  very  striking  and  the 
results  were  not  very  consistent.  In  one  instance,  a  highly  organic 
soil,  heat  decreased  the  fixing  power  for  phosphoric  acid,  while  in 
general  it  decreased  the  fixing  power  for  potash,  ammonium  nitrogen, 
and  nitrate  nitrogen.  The  effect  of  chloroform  on  the  fixation  of  the 
first  three  elements  was  negligible,  while  it  increased  the  fixing  power 
for  nitrates. 


32 

The  removal  of  the  absorbed  elements  approached  quite  rapidly  a 
constant  in  the  case  of  the  potash  and  ammonium  salts,  but  more 
slowly  in  that  of  the  phosphates.  This  was  due  to  the  excessive 
amounts  of  this  constituent  which  had  been  added.  By  reference  to 
tables  on  pages  5  and  8  it  will  be  seen  that  when  phosphates  were 
added  to  the  soil  in  light  applications  the  concentration  of  the  solution 
remained  practically  unchanged  for  an  indefinite  period. 

ACKNOWLEDGMENTS. 

Acknowledgments  are  due  and  thanks  are  hereby  extended  to  Dr. 
W.  P.  Kelley  for  valuable  suggestions  and  for  interest  shown  through- 
out this  investigation. 


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